# Multiple regions in single-region analysis type

**URL:** <https://www.simscale.com/forum/t/multiple-regions-in-single-region-analysis-type/100260>\
**Category:** Fluid Flow / CFD\
**Created:** [July 27, 2025, 3:24pm UTC](https://www.simscale.com/forum/t/multiple-regions-in-single-region-analysis-type/100260 "2025-07-27T15:24:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![norrisz](https://www.simscale.com/forum/letter_avatar/norrisz/32/5_5575768a8748004e209b776fc1b2916d.png) [@norrisz](https://www.simscale.com/forum/u/norrisz)\
**Post date:** [July 27, 2025, 3:24pm UTC](https://www.simscale.com/forum/t/multiple-regions-in-single-region-analysis-type/100260/1 "2025-07-27T15:24:07Z")

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hi there, i have some problem when doing mesh. it keep couldnt start job because  
“A setup with multiple regions is being used in a single-region analysis type. Please ensure that only one region is assigned to the material and that all other regions are assigned to a surface refinement with cell zone.”

so how to fix it?? Thankyou in advance

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**Author:** ![shenoy](https://www.simscale.com/forum/letter_avatar/shenoy/32/5_5575768a8748004e209b776fc1b2916d.png) [@shenoy](https://www.simscale.com/forum/u/shenoy)\
**Post date:** [July 28, 2025, 1:09pm UTC](https://www.simscale.com/forum/t/multiple-regions-in-single-region-analysis-type/100260/2 "2025-07-28T13:09:21Z")

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Hey @norrisz ,

As already stated in the message, you are trying to run a simulation that only accepts a single solid region in order to run. If you created a flow region for a flow simulation, then you need to [make sure to delete all other solid bodies](https://www.simscale.com/knowledge-base/flow-volume-extraction/#:~:text=If%20you%20are%20going%20to%20perform%20a%20single%20region%20analysis%20like%20incompressible%2C%20compressible%2C%20or%20convective%20heat%20transfer%2C%20you%20need%20to%20delete%20the%20solid%20body%20as%20follows%3A) (originally imported) so that only one solid flow region exists.

If you need to define [advanced concepts](https://www.simscale.com/docs/simulation-setup/advanced-concepts/) like rotating zones, then you can have additional solids in the model but you need to make sure you assign all the solids, except for the one flow region solid, an appropriate advanced concept.

I recommend you to [follow some of our flow simulation tutorials](https://www.simscale.com/docs/tutorials/tutorial-fluid-flow-through-a-valve/) to get up to speed so you can easily run your own simulations such as this one.

Feel free to share your project URL here in case you require further support. Let us know how it goes.

Best,  
Satvik